parser: support username without quotes (#3742)

parser/lexer.go

@@ -157,7 +157,7 @@ func (s *Scanner) Lex(v *yySymType) int {
 		return toHex(s, v, lit)
 	case bitLit:
 		return toBit(s, v, lit)
-	case userVar, sysVar, cast, curDate, extract:
+	case singleAtIdentifier, doubleAtIdentifier, cast, curDate, extract:
 		v.item = lit
 		return tok
 	case null:
@@ -387,7 +387,7 @@ func startWithAt(s *Scanner) (tok int, pos Pos, lit string) {
 	ch1 := s.r.peek()
 	if isIdentFirstChar(ch1) {
 		s.r.incAsLongAs(isIdentChar)
-		tok, lit = userVar, s.r.data(&pos)
+		tok, lit = singleAtIdentifier, s.r.data(&pos)
 	} else if ch1 == '@' {
 		s.r.inc()
 		stream := s.r.s[pos.Offset+2:]
@@ -401,7 +401,7 @@ func startWithAt(s *Scanner) (tok int, pos Pos, lit string) {
 			}
 		}
 		s.r.incAsLongAs(isIdentChar)
-		tok, lit = sysVar, s.r.data(&pos)
+		tok, lit = doubleAtIdentifier, s.r.data(&pos)
 	} else {
 		tok = at
 	}

parser/lexer_test.go

@@ -66,15 +66,15 @@ func (s *testLexerSuite) TestSingleCharOther(c *C) {
 	runTest(c, table)
 }
 
-func (s *testLexerSuite) TestSysOrUserVar(c *C) {
+func (s *testLexerSuite) TestAtLeadingIdentifier(c *C) {
 	defer testleak.AfterTest(c)()
 	table := []testCaseItem{
-		{"@a_3cbbc", userVar},
+		{"@a_3cbbc", singleAtIdentifier},
 		{"@-3cbbc", at},
-		{"@@global.test", sysVar},
-		{"@@session.test", sysVar},
-		{"@@local.test", sysVar},
-		{"@@test", sysVar},
+		{"@@global.test", doubleAtIdentifier},
+		{"@@session.test", doubleAtIdentifier},
+		{"@@local.test", doubleAtIdentifier},
+		{"@@test", doubleAtIdentifier},
 	}
 	runTest(c, table)
 }

parser/parser.y

@@ -47,6 +47,8 @@ import (
 %token	<ident>
 	/*yy:token "%c"     */	identifier      "identifier"
 	/*yy:token "\"%c\"" */	stringLit       "string literal"
+	singleAtIdentifier		"identifier with single leading at"
+	doubleAtIdentifier		"identifier with double leading at"
 	invalid		"a special token never used by parser, used by lexer to indicate error"
 	hintBegin	"hintBegin is a virtual token for optimizer hint grammar"
 	hintEnd		"hintEnd is a virtual token for optimizer hint grammar"
@@ -557,8 +559,6 @@ import (
 	nulleq		"<=>"
 	placeholder	"PLACEHOLDER"
 	rsh		">>"
-	sysVar		"SYS_VAR"
-	userVar		"USER_VAR"
 
 %type   <item>
 	AdminStmt		"Check table statement or show ddl statement"
@@ -1914,9 +1914,9 @@ NUM:
 	intLit
 
 Expression:
-	"USER_VAR" assignmentEq Expression %prec assignmentEq
+	singleAtIdentifier assignmentEq Expression %prec assignmentEq
 	{
-		v := $1.(string)
+		v := $1
 		v = strings.TrimPrefix(v, "@")
 		$$ = &ast.VariableExpr{
 				Name: 	  v,
@@ -1988,9 +1988,9 @@ Factor:
 	{
 		$$ = &ast.BinaryOperationExpr{Op: $2.(opcode.Op), L: $1.(ast.ExprNode), R: $3.(ast.ExprNode)}
 	}
-|	Factor CompareOp "USER_VAR" assignmentEq PredicateExpr %prec assignmentEq
+|	Factor CompareOp singleAtIdentifier assignmentEq PredicateExpr %prec assignmentEq
 	{
-		v := $3.(string)
+		v := $3
 		v = strings.TrimPrefix(v, "@")
 		variable := &ast.VariableExpr{
 				Name: 	  v,
@@ -4927,9 +4927,9 @@ VariableAssignment:
 	{
 		$$ = &ast.VariableAssignment{Name: $2, Value: $4.(ast.ExprNode), IsSystem: true}
 	}
-|	"SYS_VAR" eq SetExpr
+|	doubleAtIdentifier eq SetExpr
 	{
-		v := strings.ToLower($1.(string))
+		v := strings.ToLower($1)
 		var isGlobal bool
 		if strings.HasPrefix(v, "@@global.") {
 			isGlobal = true
@@ -4943,15 +4943,15 @@ VariableAssignment:
 		}
 		$$ = &ast.VariableAssignment{Name: v, Value: $3.(ast.ExprNode), IsGlobal: isGlobal, IsSystem: true}
 	}
-|	"USER_VAR" eq Expression
+|	singleAtIdentifier eq Expression
 	{
-		v := $1.(string)
+		v := $1
 		v = strings.TrimPrefix(v, "@")
 		$$ = &ast.VariableAssignment{Name: v, Value: $3.(ast.ExprNode)}
 	}
-|	"USER_VAR" assignmentEq Expression
+|	singleAtIdentifier assignmentEq Expression
 	{
-		v := $1.(string)
+		v := $1
 		v = strings.TrimPrefix(v, "@")
 		$$ = &ast.VariableAssignment{Name: v, Value: $3.(ast.ExprNode)}
 	}
@@ -5005,9 +5005,9 @@ Variable:
 	SystemVariable | UserVariable
 
 SystemVariable:
-	"SYS_VAR"
+	doubleAtIdentifier
 	{
-		v := strings.ToLower($1.(string))
+		v := strings.ToLower($1)
 		var isGlobal bool
 		if strings.HasPrefix(v, "@@global.") {
 			isGlobal = true
@@ -5023,21 +5023,25 @@ SystemVariable:
 	}
 
 UserVariable:
-	"USER_VAR"
+	singleAtIdentifier
 	{
-		v := $1.(string)
+		v := $1
 		v = strings.TrimPrefix(v, "@")
 		$$ = &ast.VariableExpr{Name: v, IsGlobal: false, IsSystem: false}
 	}
 
 Username:
-	stringLit
+	StringName
 	{
-		$$ = $1 + "@%"
+		$$ = $1.(string) + "@%"
 	}
-|	stringLit "AT" stringLit
+|	StringName "AT" StringName
 	{
-		$$ = $1 + "@" + $3
+		$$ = $1.(string) + "@" + $3.(string)
+	}
+|	StringName singleAtIdentifier
+	{
+		$$ = $1.(string) + $2
 	}
 
 UsernameList:

parser/parser_test.go

@@ -1412,6 +1412,24 @@ func (s *testParserSuite) TestPrivilege(c *C) {
 	table := []testCase{
 		// for create user
 		{`CREATE USER 'test'`, true},
+		{`CREATE USER test`, true},
+		{"CREATE USER `test`", true},
+		{"CREATE USER test-user", false},
+		{"CREATE USER test.user", false},
+		{"CREATE USER 'test-user'", true},
+		{"CREATE USER `test-user`", true},
+		{"CREATE USER test.user", false},
+		{"CREATE USER 'test.user'", true},
+		{"CREATE USER `test.user`", true},
+		{"CREATE USER uesr1@localhost", true},
+		{"CREATE USER `uesr1`@localhost", true},
+		{"CREATE USER uesr1@`localhost`", true},
+		{"CREATE USER `uesr1`@`localhost`", true},
+		{"CREATE USER 'uesr1'@localhost", true},
+		{"CREATE USER uesr1@'localhost'", true},
+		{"CREATE USER 'uesr1'@'localhost'", true},
+		{"CREATE USER 'uesr1'@`localhost`", true},
+		{"CREATE USER `uesr1`@'localhost'", true},
 		{`CREATE USER IF NOT EXISTS 'root'@'localhost' IDENTIFIED BY 'new-password'`, true},
 		{`CREATE USER 'root'@'localhost' IDENTIFIED BY 'new-password'`, true},
 		{`CREATE USER 'root'@'localhost' IDENTIFIED BY PASSWORD 'hashstring'`, true},